Laptop suddenly died, what to do?

Hi, the laptop I'm referring to is hp's compaq nc6220. It's quite old and I'm pretty positive that it's battery died. The reason I believe so is because it ran fine when plugged in but wouldn't work otherwise (could be wrong though, I'm far from an expert).
Anyway, I was using it normaly browsing the internet and it just died. I couldn't turn it on. I thought at the moment that the plug fell out or something (happened sometimes) but no, everything was fine. Tried using other outlets: nothing. The only thing that's worth mentioning is that the LED light flickered when the plug that goes into the laptop was at a certain angle but for a brief moment.
What can I do here? Is the info enough for a possible diagnosis? If so can I revive my old laptop? If not is there a way of recovering the data from it?
Thank you in advance :)

P.S. sorry if my terminology is not correct